Motor frame assemblies are employed in floor care equipment or other devices which require use of blower fans. Common motor frame assemblies are made from a three-piece construction consisting of a fan end bracket, a blower shell and a motor housing. Generally, the motor frame is assembled by inserting a motor with an axial shaft into the fan end bracket. A blower fan is then secured to the end of the motor shaft extending through the fan end bracket and enclosed by the blower shell. Next, the motor is enclosed by the motor housing which fits over the fan end bracket and at least a portion of the blower shell. The fan end bracket, the blower shell and the motor housing are then positively secured to one another by fasteners.
The above assembly relies on various-height and various-location individual contact points supported by brackets, in axial load, to ensure a secure and seated fit between all three pieces. Due to the highly-irregular shapes of the three pieces, which are typically made of molded thermoplastic or thermoset material, the brackets vary in size due to shrinkage, which results in inadequate seating of the three pieces in the final assembly. As a result, the motor armature core rubs against the field core, requiring hand-fitting of the motors into the motor frame assembly. As will be appreciated, this situation is not conducive for high-volume production.
When the above motor frame assembly pieces are secured to one another, other alignment problems became apparent. In particular, the ball bearings, which are fitted upon the motor shaft between the pieces, would not be properly aligned with the motor shaft, causing bearing stress, added noise and short bearing life. Moreover, this misalignment increases the vibration of the motor frame assembly, causing the fasteners which hold the three pieces together to absorb vibrational stress. Ultimately, this vibrational stress causes the fasteners to loosen and further harm operation of the motor within the assembly.
Based upon the foregoing, there is a need in the art for a motor frame assembly with alignment features. Moreover, there is a need in the art for a motor frame assembly which provides axial, radial and angular alignment with respect to the three assembled pieces of a motor frame assembly.